Hi Matthew,

[auto build test ERROR on drm-intel/for-linux-next]
[also build test ERROR on next-20170407]
[cannot apply to v4.11-rc5]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Matthew-Auld/drm-i915-initial-support-for-huge-gtt-pages-V2/20170406-060958
base:   git://anongit.freedesktop.org/drm-intel for-linux-next
config: x86_64-randconfig-s0-04090705 (attached as .config)
compiler: gcc-4.4 (Debian 4.4.7-8) 4.4.7
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   cc1: warnings being treated as errors
   drivers/gpu/drm/i915/i915_gem_gtt.c: In function 'gen8_ppgtt_insert_4lvl':
>> drivers/gpu/drm/i915/i915_gem_gtt.c:1002: error: 'iter' is used uninitialized in this function
   drivers/gpu/drm/i915/i915_gem_gtt.c: In function 'gen8_ppgtt_insert_3lvl':
   drivers/gpu/drm/i915/i915_gem_gtt.c:983: error: 'iter.sg' is used uninitialized in this function
   drivers/gpu/drm/i915/i915_gem_gtt.c:984: error: 'iter.dma' is used uninitialized in this function

vim +/iter +1002 drivers/gpu/drm/i915/i915_gem_gtt.c

894ccebee Chris Wilson 2017-02-15   996  				   enum i915_cache_level cache_level,
894ccebee Chris Wilson 2017-02-15   997  				   u32 unused)
894ccebee Chris Wilson 2017-02-15   998  {
894ccebee Chris Wilson 2017-02-15   999  	struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
894ccebee Chris Wilson 2017-02-15  1000  	struct sgt_dma iter = {
894ccebee Chris Wilson 2017-02-15  1001  		.sg = pages->sgl,
894ccebee Chris Wilson 2017-02-15 @1002  		.dma = sg_dma_address(iter.sg),
894ccebee Chris Wilson 2017-02-15  1003  		.max = iter.dma + iter.sg->length,
894ccebee Chris Wilson 2017-02-15  1004  	};
894ccebee Chris Wilson 2017-02-15  1005  	struct i915_page_directory_pointer **pdps = ppgtt->pml4.pdps;

:::::: The code at line 1002 was first introduced by commit
:::::: 894ccebee2b0e606ba9638d20dd87b33568482d7 drm/i915: Micro-optimise gen8_ppgtt_insert_entries()

:::::: TO: Chris Wilson <chris@chris-wilson.co.uk>
:::::: CC: Chris Wilson <chris@chris-wilson.co.uk>

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